平紋編織復(fù)合材料層壓板低速沖擊后剩余強度分析
發(fā)布時間：2018-08-08 19:01
【摘要】：平紋編織型復(fù)合材料由于具有比強度高、質(zhì)量輕和穩(wěn)定性能好等特性,在航空等結(jié)構(gòu)中的應(yīng)用越來越廣泛。但平紋編織復(fù)合材料抗沖擊性能差,受沖擊作用后結(jié)構(gòu)內(nèi)部容易出現(xiàn)纖維斷裂、基體裂紋及分層等現(xiàn)象,嚴重損害結(jié)構(gòu)的承載能力,從而引發(fā)安全事故。為了評估結(jié)構(gòu)的損傷容限,因此對復(fù)合材料受沖擊后的壓縮性能開展研究具有重要的意義。本文基于ASTM D7136標準對三種鋪層層壓板進行低速沖擊試驗,研究了其沖擊損傷特性;采用Abaqus有限元分析軟件進行了低速沖擊過程的動態(tài)模擬,揭示其損傷規(guī)律。為分析層壓板沖擊后剩余強度,進行壓縮試驗,得到?jīng)_擊能量與剩余強度的關(guān)系;并將有限元模擬中的沖擊損傷后末狀態(tài)作為壓縮的數(shù)值模擬的起始狀態(tài)來實現(xiàn)層壓板沖擊及沖擊后壓縮的銜接。最后,進行了濕熱環(huán)境下含沖擊損傷層壓板的壓縮試驗。(1)對三種鋪層層壓板進行了不同能量的沖擊試驗,發(fā)現(xiàn)三條凹坑深度-沖擊能量曲線都會出現(xiàn)拐點;通過超聲C掃描得出,在拐點前層壓板內(nèi)部主要出現(xiàn)分層損傷,拐點后沖擊背面伴隨有纖維斷裂及基體開裂現(xiàn)象。建立層壓板沖擊模型,采用Hashin失效準則對面內(nèi)損傷進行預(yù)判,引入cohesive單元模擬層間損傷,并采用Quads準則作為界面初始損傷判據(jù)。計算結(jié)果顯示層壓板分層損傷面積類似花生狀、橢圓形等,分層損傷面積也與試驗值接近。三種層壓板的分層損傷都是由沖擊背面向正面擴展的,模擬結(jié)果也可以發(fā)現(xiàn)少量的纖維斷裂損傷及基體開裂損傷。(2)含沖擊損傷層壓板壓縮過程中出現(xiàn)局部屈曲以及分層擴展等現(xiàn)象,最終發(fā)生剪切分層失效。并且剩余強度會受沖擊能量的影響,沖擊能量越大,剩余強度就下降的越多;相比于無損層壓板,其剩余強度都不同程度的下降了30%到62.5%。在含損傷層壓板數(shù)值模擬后處理中發(fā)現(xiàn):壓縮損傷會在沖擊損傷區(qū)域逐漸向周圍擴展,并且90度鋪層方向擴展的最快,45度和-45度次之,0度方向最慢;模擬的壓縮破壞載荷較試驗值比較吻合。(3)相比常溫下含沖擊損傷層壓板,吸濕后的層壓板破壞載荷下降超過10%,說明濕熱效應(yīng)會使層壓板結(jié)構(gòu)壓縮性能降低。
[Abstract]:Plain braided composites are widely used in aeronautical structures because of their high specific strength, light weight and good stability. However, the impact resistance of plain braided composites is poor, and fiber fracture, matrix cracks and delamination are easy to appear in the structure after the impact, which seriously damages the bearing capacity of the structure and causes safety accidents. In order to evaluate the damage tolerance of structures, it is of great significance to study the compressive properties of composites after impact. In this paper, three kinds of laminated laminates are subjected to low speed impact tests based on ASTM D7136 standard, and their impact damage characteristics are studied, and the dynamic simulation of low speed impact process is carried out by using Abaqus finite element analysis software to reveal the damage law. In order to analyze the residual strength of laminates after impact, the relation between impact energy and residual strength was obtained by compression test. The final state of impact damage in finite element simulation is taken as the initial state of compression numerical simulation to realize the connection of laminated plate impact and post-impact compression. Finally, the compression tests of laminates with impact damage were carried out in humid and hot environment. (1) three kinds of laminated laminates with different energy were tested with different energy, and it was found that the inflection points appeared in the three crater depth-impact energy curves; The ultrasonic C scan shows that the laminated laminates are mainly delaminated at the inflexion point, and there is fiber fracture and matrix cracking on the back of the impact after the inflection point. A laminated plate impact model was established, and the Hashin failure criterion was used to predict the internal damage. The cohesive element was introduced to simulate the interlaminar damage, and the Quads criterion was used as the initial damage criterion of the interface. The results show that the delamination damage area of laminate is similar to that of peanut, ellipse and so on, and the delamination damage area is close to the experimental value. The delamination damage of all three laminates extends from the back of the impact to the front. The simulation results also show a small amount of fiber fracture damage and matrix cracking damage. (2) Local buckling and delamination propagation occur during compression of laminates with impact damage and finally shear delamination failure occurs. And the residual strength will be affected by the impact energy, the larger the impact energy, the more the residual strength will decrease, and compared with the non-destructive laminates, the residual strength of the laminates will be reduced by 30% to 62.5% in varying degrees. In the post-processing of numerical simulation of laminates with damage, it is found that compression damage will gradually expand around the impact damage area, and the fastest spreading direction in the direction of 90 degrees layer is 45 degrees and -45 degrees followed by zero degrees. The simulated compressive failure load is in good agreement with the experimental value. (3) compared with the laminated plate with impact damage at room temperature, the damage load of the hygroscopic laminate decreases by more than 10%, which indicates that the hygrothermal effect will reduce the compressibility of laminate structure.
【學(xué)位授予單位】：南昌大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB33
[Abstract]:Plain braided composites are widely used in aeronautical structures because of their high specific strength, light weight and good stability. However, the impact resistance of plain braided composites is poor, and fiber fracture, matrix cracks and delamination are easy to appear in the structure after the impact, which seriously damages the bearing capacity of the structure and causes safety accidents. In order to evaluate the damage tolerance of structures, it is of great significance to study the compressive properties of composites after impact. In this paper, three kinds of laminated laminates are subjected to low speed impact tests based on ASTM D7136 standard, and their impact damage characteristics are studied, and the dynamic simulation of low speed impact process is carried out by using Abaqus finite element analysis software to reveal the damage law. In order to analyze the residual strength of laminates after impact, the relation between impact energy and residual strength was obtained by compression test. The final state of impact damage in finite element simulation is taken as the initial state of compression numerical simulation to realize the connection of laminated plate impact and post-impact compression. Finally, the compression tests of laminates with impact damage were carried out in humid and hot environment. (1) three kinds of laminated laminates with different energy were tested with different energy, and it was found that the inflection points appeared in the three crater depth-impact energy curves; The ultrasonic C scan shows that the laminated laminates are mainly delaminated at the inflexion point, and there is fiber fracture and matrix cracking on the back of the impact after the inflection point. A laminated plate impact model was established, and the Hashin failure criterion was used to predict the internal damage. The cohesive element was introduced to simulate the interlaminar damage, and the Quads criterion was used as the initial damage criterion of the interface. The results show that the delamination damage area of laminate is similar to that of peanut, ellipse and so on, and the delamination damage area is close to the experimental value. The delamination damage of all three laminates extends from the back of the impact to the front. The simulation results also show a small amount of fiber fracture damage and matrix cracking damage. (2) Local buckling and delamination propagation occur during compression of laminates with impact damage and finally shear delamination failure occurs. And the residual strength will be affected by the impact energy, the larger the impact energy, the more the residual strength will decrease, and compared with the non-destructive laminates, the residual strength of the laminates will be reduced by 30% to 62.5% in varying degrees. In the post-processing of numerical simulation of laminates with damage, it is found that compression damage will gradually expand around the impact damage area, and the fastest spreading direction in the direction of 90 degrees layer is 45 degrees and -45 degrees followed by zero degrees. The simulated compressive failure load is in good agreement with the experimental value. (3) compared with the laminated plate with impact damage at room temperature, the damage load of the hygroscopic laminate decreases by more than 10%, which indicates that the hygrothermal effect will reduce the compressibility of laminate structure.
【學(xué)位授予單位】：南昌大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB33
【參考文獻】
相關(guān)期刊論文 前10條
1 饒輝;許希武;朱煒W，
本文編號：2172718
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